The hypothesis that cooperation among organization is more likely where personal contacts exist among their leaders has been supported by a few studies, dedicated both to movements and to political organization in the wider sense. In both cases it has become clear that the leaders of organization who work or campaign together tend to be linked by shared experiences which precede the formation of the coalition itself. The denser the relationships among the leaders and the activists of various movement organization, the higher the chances of cooperation among them. There is no reason to think that the impact of networks which pre-date the emergence of a particular movement is limited to individual decisions to participate ; rather, they also influence opportunities for cooperation among organization